A polymer electrolyte fuel cell (PEFC) is known as one kind of the fuel cell. A fuel cell of the polymer electrolyte fuel cell includes an anode acting as a fuel electrode and a cathode acting as an oxidizer electrode, and a solid polymer electrolyte membrane sandwiched between the anode and cathode. The polymer electrolyte fuel cell is so configured that a plurality of elements each composed of a fuel cell sandwiched between separators are stacked one on top of another.
In the case of an in-car polymer electrolyte fuel cell, maneuverability is regarded as important and therefore there are many systems that use pure hydrogen as fuel and air as an oxidizer.
However, in the case of a stationary or a household polymer electrolyte fuel cell, a system that uses town gas or propane gas full of methane components as fuel has been desired from the standpoint of an infrastructure problem. In this case, it is common practice to use a fuel processor that produces hydrogen by mixing water vapor with fuel to reform fuel into hydrogen.
In any system, hydrogen supplied to the anode side is ionized, flows in a solid polymer electrolyte membrane, and reacts with oxygen on the cathode side to produce water and generate electric energy outside.
The polymer electrolyte fuel cell generates not only electric energy but also exhaust heat of not higher than 100° C. This is because the heat dissipation from the high cell temperature toward the ambient temperature takes place in the form of heat. In the fuel processor for reforming fuel into hydrogen, too, a combustor is generally used for heating in reforming reaction in a reformer or the like, with the result that exhaust heat is generated by combustion exhaust gas or comes from outside the fuel processor.
Use of heat generated when such a fuel cell generates electricity enables hybrid operation with electric energy, that is, cogeneration operation, which makes it possible to realize a very economical, energy-efficient, environmentally friendly operation.
In recent years, developments have been made to introduce such a fuel-cell power generation system into homes. In Japan, the practical use of such a fuel-cell power generation system is already in progress. The fuel-cell power generation system emits a smaller amount of carbon dioxide and is superior in environmental preservation and energy saving. Therefore, attention is being focused on the fuel-cell power generation system as an energy system capable of preventing global warming.
The fuel-cell power generation system can be installed in more places as it is smaller in size and requires a smaller installation area, resulting in an expansion of the market size and the popularization of energy-saving devices. In addition, as the system becomes smaller and lighter in weight, it is easier to move the system for installation, improving its merchantability.
Accordingly, to promote the popularization of the fuel-cell power generation system, not only an improvement in the basic performance of the system, including power generation efficiency and exhaust heat efficiency, but also a highly manufacturable configuration capable of size reduction are desired.